A wideband compact series-fed patch subarray is proposed for 79 GHz multiple-input—multiple-output (MIMO) radar. The proposed subarray is, for the first time, loaded with stacked micro-vias (SMVs). Two sets of patches in the subarray are fed 180° out-of-phase. A low-cost, high-resolution multilayer printed circuit board (PCB) technology, called “any-layer PCB,” is used to implement the SMVs, which cannot be done by standard high-definition interconnect PCB technology. Moreover, the technology supports small SMVs on different layers; hence, thick machine-drilled vias can be avoided. For comparison, a series-fed patch subarray with no SMV loading is designed. It is shown that SMV loading facilitates a larger overlap of the impedance and gain bandwidths, leading to a larger operating bandwidth. The measured 10 dB impedance and 3 dB gain bandwidths are 15% and 9.6%, respectively. The sidelobe suppression is above 12.9 dB, and the maximum array gain is 12.67 dBi at 79.1 GHz. This subarray is suitable for MIMO radar, as its width is around half-wavelength and the SMVs around it mitigate the crosstalk between the transmitting and receiving arrays.

A novel strategy is proposed to design microstrip antenna arrays with two wide bands for high-frequency applications using any-layer HDI PCB technology. This technology makes it possible to stack multiple layers of substrates and microvias. Several antennas are designed and taped out to illustrate the new procedure. The antennas cover two wide frequency bands with a large separation ratio of 2.2:1, from 28 to 30 GHz and from 57 to 71 GHz. Measurement results show a matching better than 10 dB over both bands, and an intraband coupling lower than −28 dB. Measured gains and radiation patterns for the arrays all show a good agreement with simulations.

A parasitic patch antenna array based on a new multi-layer PCB technology, called the Any-Layer PCB technology, is presented. The antenna is designed for 77-81 GHz MIMO radar systems, mainly for automotive applications. The designed antenna array is composed of 4 sub-arrays. Each sub-array is based on 2 parasitic patches which are excited by a feeding patch. With this feeding topology, the radiation pattern and gain of the proposed antenna are nearly constant across the whole 4 GHz bandwidth, which is a very attractive feature for radar designers. A prototype has been fabricated and measured. The gain and SLL are 10.22, and -14.11 dB at 79 GHz, respectively.

This paper proposes a substrate integrated waveguide (SIW) slot antenna array for the wideband gigabyte mobile radio application in the E-band. The wideband unit cell design is based on simultaneous feeding of four-element radiation slots with a higher order cavity mode directly excited by a simple slot aperture fed by a microstrip fork-like tuning stub. Employing the higher order mode along with the slot aperture facilitates low loss, simple feeding network, and lower sensitivity to fabrication errors. To cancel the beam tilt versus frequency, the higher-order-mode unit cell is used in a 2 x 2 array along with a differential feeding structure. The array was designed and taped out using a new high-resolution multilayer printed circuit board (PCB) technology and characterized by using the constructed millimeter-wave (mm-wave) measurement setup at KU Leuven/imec. This technology provides the possibility to stack microvias in PCBs and reduces the fabrication cost compared to other multilayer technologies in mm-wave bands. The proposed array in 2 x 2 array configuration has a measured bandwidth of 11.4 GHz (16%), a total efficiency of 69%, a realized gain of 12 dBi at 72 GHz, and a 3-dB gain bandwidth that covers the entire impedance bandwidth. In comparison with existing E-band SIW slot arrays (compensating for array sizes), the proposed design achieves similar or better performance in bandwidth but with lower cost, lower sensitivity to fabrication tolerances, and higher total efficiency.

In this article, a new wideband cavity-backed bow-tie microstrip antenna is presented for short-range 77-81 GHz radar applications. The design is based on a subarray consisting of two single elements. Each element consists of a multilayer bow-tie patch antenna surrounded by a metallic cavity to suppress the surface waves and parallel plate modes. The subarray elements are fed through a laminated waveguide with 180 degrees phase shift. An eight-layer build-up and a new advanced multilayer PCB technology, the so-called any-layer PCB technology, is used for the fabrication. The performance of this antenna has been verified by both simulations and measurements. A bandwidth of more than 8% is achieved. The gain is 7.9 dBi, and the radiation efficiency is 70% at 79 GHz. Beam widths of 84 degrees in the E-plane and 48 degrees in the H-plane are obtained, which are compatible with radar requirements for short-range applications.

A new wideband cavity-backed aperture coupled microstrip antenna is presented for 79 GHz short-range multi-input multi-output radar applications. This design is based on a sub-array consisting of two single elements, and each element is founded on a cavity backed aperture coupled patch antenna. A microstrip to strip-line transition and a series feeding topology is used to feed the elements. The antennas are manufactured by using a new high-resolution multi-layer PCB technology. This technology is able to deliver high-resolution stacked micro-vias on very thin substrates. The performance of the designed antenna has been verified by both simulations and measurements. The bandwidth is 11.2%, and the maximum gain and efficiency are 6.05 dBi and 80% along 77–81 GHz.

A wideband microstrip comb-line antenna array is developed for 79 GHz multiple-input-multiple-output radar applications. This array is composed of four radiating subarrays, with 180 degrees phase shift. This topology leads to a more stable radiation pattern behavior and broadside gain flatness along the frequency bandwidth. The antenna is taped out with a new high-resolution multilayer printed circuit board (PCB) technology, called "anylayer PCB." This technology provides the possibility to stack small microvias, instead of using thick machine-drilled vias. A measured impedance and gain bandwidth of 12.5% is achieved. The sidelobe suppression is higher than 15 dB, and the array gain is 12.36 dBi at 79 GHz.

A novel wide band compact grid antenna array is developed for 79 GHz MIMO radar applications. The key issue is the stable radiation pattern with flat gain characteristic along the whole frequency bandwidth, which is very advantageous for the targeted radar applications. The antenna is taped out with the new high resolution multi-layer PCB technology, called "Any-Layer PCB". This technology provides the possibility to stack micro-vias in PCB boards and reduce the fabrication cost compared to other multi-layer technologies in mm-wave bands. With this feature, the width of the array has been compacted with 17.2%, which leads to a higher side lobe suppression and an enhancement of the field of view in radar applications. A combined impedance and 3-dB gain band width of 9.6% is achieved. The gain and SLL are 13.52 dB and -14 dB at 79 GHz, respectively.

In this paper, a new single element wideband cavity backed multi-layer microstrip patch antenna is presented. For this antenna, rectangular patch and circular cavity has been used. This antenna is designed for 79 GHz short range radar applications, and is fabricated with advanced high resolution "Any-Layer" PCB technology. It has a wide bandwidth of 12.44 GHz, which is 15.6% of the center frequency. The beam widths in both E and H-planes are very wide, and are 140 degrees and 78 degrees respectively. In addition, the antenna has a relative gain and efficiency of 5.11 dB and 89.2% respectively. Furthermore, measurements have been done, and show a good agreement with simulations.

An 8-way phased array TRX front-end with RF phase shifting and on-chip TR switching is implemented in 28nm CMOS . The TX OP1dB and RX NF are 10dBm and 6.8dB, respectively. The active phase shifter shows less than 5° phase resolution and amplitude errors within ±0.35dB. The 9.6mm 2 chip consumes 231mW in RX and 508mW in TX mode from a 0.9 V supply. When combined with PCB antennas, a ±46° scan angle is obtained with <0.4dB peak-to-peak gain ripples without calibration.

In this paper, a 79 GHz microstrip antenna subarray, optimized for operation in a Phase Modulated Continuous Wave (PMCW) MIMO radar demonstrator is presented. The antenna combines all necessary features for this very specific type of applications. First of all, the spillover between transmit and receive channels in such a system is reduced by the combined effect of a microvia cage and the arraying of two elements. Second, it shows a wide band of 13.5%. Third, a wide beam in the E-plane (136 degrees), necessary for scanning, and a much smaller beamwidth in H-plane (36 degrees), advantageous to reduce mutual coupling, are realized. Finally, it has been fabricated with the advanced so-called "Any-Layer" technology. This technology is as accurate as other advanced technologies in the millimeter wave bands, but at a much lower cost, and thus very suited for mass production. The gain and radiation efficiency were simulated to be 7.44 dBi and 83%, respectively.

In this paper, new wideband cavity backed aperture coupled microstrip antenna is presented for 79 GHz MIMO radar applications. This designs is based on a sub-arrays consisting of two single elements, which have stacked rectangular patch radiators. A microstrip to stripline transition and a series feeding topology is used to feed the elements. The antennas are manufactured by using a new high resolution multi-layer PCB technology. The performance of this antennas have been verified by both simulations and measurements. Antenna bandwidth is 9.7%, and the gain is more than 5.2dBi. Large beam widths of 138 degrees in E-plane and 40 degrees in H-plane are obtained. Antenna radiation efficiency is more than 75%, the mutual coupling between the array elements is less than -18dB.

In this paper, a new single element broad band cavity backed multi-layer microstrip patch antenna is presented. This antenna is designed to be used in 79 GHz MIMO radar applications, and is fabricated with advanced high resolution multi-layer PCB technology. It has a wide bandwidth of 11.43 GHz, which is 14.5% of the center frequency. The beam widths in both E and H-planes are very wide, and are 144 degrees and 80 degrees respectively. Also, the antenna gain and efficiency are respectively 4.7 dB and 87%. Furthermore, measurements have been done, and show a good agreement with simulations.

Millimeter-Wave transceivers with beamforming capabilities, such as the one presented in this work, are a key technology to reach 4 or 6Gb/s at 10m range with the IEEE 802.11ad standard. Moreover, for mm-Wave access in 5G it will also be necessary to boost peak data-rates far beyond 1Gb/s at hundreds of meters in small cells. Transceiver architectures with beamforming often combine superheterodyne with RF beamforming [1], leading to a high power consumption and a suboptimal RX noise figure due to losses in the beamforming circuitry. In contrast, the 57-to-66GHz TRX IC presented in this paper, whose architecture is depicted in Fig. 13.5.1, uses direct conversion and analog baseband beamforming. Direct-conversion radios are inherently simpler than superheterodyne and do not have to cope with the image frequency, but on the other hand they may suffer from pulling of the PA on the VCO. In this work this is avoided by the non-integer ratio of 2.5 between the operating frequency and the 24GHz PLL that subharmonically injection locks a 60GHz quadrature oscillator (Fig. 13.5.2).

Millimeter wave sensing systems suffer from measurement inaccuracies when the waist of the radiated beam is relatively larger than the size of the test targets. In order to mitigate the issue, we designed a quasi-optical lens system, which enhances the dynamic range and sensitivity of the millimeter wave sensor system, compared with lens-less sensor systems.

This paper presents a 60 GHz TX/RX chipset in 40 nm CMOS technology flip-chip mounted on a multilayer organic package with integrated phased-array antennas. The TX/RX chips perform phase shifting of 4 antenna paths in analog baseband. Short range (< 5 m) gigabit communication is proven by measurement of a wireless link between TX and RX modules.

A polar transmitter (TX) is implemented at 60 GHz, enabling a power amplifier (PA) to operate in saturation where efficiency is highest, even when handling higher order modulations such as QPSK and 16-QAM. The phase path is upconverted by I-Q mixers, while the amplitude path modulates an RF-DAC. Aimed at 802.11ad applications, the 10 GS/s (i.e., 6x-oversampled) polar TX realizes more than 30 dB alias attenuation, and the input bandwidth exceeds 3.1 GHz. The PA saturated output power is 10.8 dBm with 29.8% drain efficiency at the maximum RF-DAC code. Average output power is 8.1 dBm with 22.3% drain efficiency at -20.7 dB EVM for QPSK modulation without RF-DAC predistortion. The corresponding 16-QAM values are: 7.2 dBm average output power with 19.8% efficiency at -16.5 dB EVM. With predistortion, a QPSK modulated output achieves 5.3 dBm average power with 15.3% efficiency at -23.6 dB EVM, while 3.6 dBm average power with 11.6% efficiency at -18.1 dB EVM is realized for 16-QAM. For a sampling rate of 10 GS/s, the TX data rates are 3.33 Gb/and 6.67 Gb/s for QPSK and 16-QAM, respectively. Implemented in 40 nm bulk-CMOS, the core circuit occupies 0.18 mm2 core of the 2.38 mm2 total die area, and consumes 40.2 mW from a 0.9 V supply.

An integrated high dynamic range approach is presented to accurately measure the radiation pattern, the scattering parameters, and the gain of integrated on-wafer antennas operating in the millimeter-wave frequency band. To avoid interconnection problems such as connector mounting, RF probes are used to connect to the antenna. This measurement system is specially designed to avoid scattering and parasitic radiation of RF probes in order to increase the dynamic range of the measurements. The mm-wave frequency band is split into two with each band having its own conceptual solution, and a special gain measurement technique is foreseen. The proposed system shows at least a 20 dB increment in the measurement dynamic range. Also, it can measure the nulls of a radiation pattern with much higher precision, down to ca. -30 dBi with respect to the maximum. This is much lower than most systems described in open literature. The setup is intended to work between 30-90 GHz.